The use of construction and demolition wastes (CDW) as alternative material in engineering has proved promising applications, especially in pavement layers. However, the high grain breakage of this material has led to uncertainties regarding its performance. The present study assessed the effect of compaction energy on grain breakage of CDW, comparatively to a local sandy-clay (SC) soil with gravels, and mixtures of soil-CDW. Other geotechnical properties were also evaluated for application in pavements. Results showed the feasibility of using CDW as pavement layer material when compacted using modified energy. The local sandy-clay soil was not appropriate for pavement layers, while soil-CDW mixture improved soil geotechnical characteristics, allowing its use as subbase course. Grain breakage analysis, based on a statistical approach, showed that CDW undergoes greater particle size distribution change, not altered by compaction energy increase. Results confirmed that soil-CDW mixture presented superior performance for pavement layers.

The aim of this paper is to evaluate the relationship between pore-size distribution and compressibility of a lateritic soil. Soil fabric was analysed under different conditions of preparation: compacted, reconstituted and intact, by means of mercury intrusion porosimetry tests on loading to different stress levels. The results show that all samples present bimodal pore distribution. However, the conditions of preparation and loading affected macropores more intensely, with subtle effects on micropores. This behaviour was attributed to the presence of aggregations with cementation. The compression curve of macro and micropores were determined and it was observed that the compression curve of macropores is very similar to the compression curve of the samples. In addition, it was observed that the fabric parameter regarding the uniformity of macro and micropores changed during loading. The new fabric parameter proposed captures the change in pore uniformity with loading. This parameter appears to be related to the soil compressibility, indicating that the most compressible samples also show greater changes in the uniformity of macropores.

Soil compaction is one of the most common techniques used to engineer the soil. It is especially appealing to developing countries for its cost-effective and sustainable attributes for improving the soil's geotechnical characteristics. The compaction process along with the complexity of residual soils, abundant in the tropics zone, can have an impact on the performance of geotechnical structures built with these soils. Therefore, it is important to understand the influence that certain compaction conditions have on the structure of these materials. To investigate that, mercury intrusion porosimetry tests were performed on compacted samples of a tropical residual soil from Brazil under different conditions of water content and compactive effort. Results show that the compacted soil under all studied conditions presents a bimodal pore-size distribution (PSD). It appears that the low availability of water within the macro-pores, hence suction, could have played a decisive role in maintaining the bimodal framework of the PSD. In this respect, this study contributes to a better understanding of the tropical residual soils’ structure when subjected to different compaction conditions, thus providing means to improve field applications.

Os agregagos de resíduos da construção civil e demolição (RCD) possuem grande potencial de aplicação em obras de drenagem e pavimentação, quando atendidos os requisitos previstos pelas normas técnicas vigentes. Pesquisas apontam para a possível quebra de grãos mediante esforços de compactação no campo. Assim, esta pesquisa teve como objetivo avaliar a viabilidade de uso de RCD e mistura solo-RCD em camadas de pavimentos, bem como uma avaliação da potencial quebra dos agregados durante o processo de compactação e após análises de Índice de Suporte Califórnia (CBR) e compressão edométrica. Os limites de consistência indicaram o RCD como redutor de plasticidade. Através dos resultados obtidos constatou-se que o RCD e a mistura solo-RCD atendem aos requisitos de CBR e expansão para reuso como material de reforço do subleito, sub-base e até base de pavimentos para determinados teores de umidade. Na análise de quebra, identificou-se menor resistência do RCD em relação a mistura solo-RCD. Os índices de quebra determinados mostraram mudanças na distribuição granulométrica do RCD e da mistura solo-RCD como dependentes do teor de umidade do material. Os resultados indicaram que a quebra dos grãos ocorre com maior intensidade para os agregados do RCD em altas tensões, sugerindo o uso da mistura solo-RCD.

Compacted soils are a common component of engineering structures worldwide. In tropical regions, lateritic soils exhibit distinct characteristics due to soil aggregation from iron and aluminum hydroxides and their bimodal structure. However, the compaction process can alter soil structure and mechanical behavior. This paper aims to assess the effects of soil structure on the saturated and unsaturated mechanical behavior of a lateritic soil under different compacted energies. The methodology involves porosimetry, retention curve and saturated and unsaturated triaxial tests, using appropriate standards and references. Under saturated conditions, these structural variations affected the volumetric behavior at the critical state, particularly in samples compacted on the dry side of the compaction curve. Additionally, a unique Critical State Line (CSL) could be traced for all samples in the p’ x q space. Under unsaturated conditions, the effects of soil structure were evident, with both the volumetric response and shear strength increase being influenced by suction. Samples molded with no compaction energy, or non-proctor energy, resulted in higher macropore void ratio leading to more pronounced volumetric contraction during shear and less gain in shear strength. Therefore, this work contributes to the understanding of the behavior of compacted laterite soils, providing valuable information for projects involving compacted laterite soils in the field, such as dams, embankments and pavement subgrade.